(Business 2.0) – Last year's successful test of SpaceShipOne got plenty of people excited about the prospect of space tourism--but let's face it, nobody's dusting off their Vulcan-to-English dictionary quite yet. That may change, however, if the April 30 launch of Cosmos 1 fares as well. Built for just $4 million and managed by the privately funded Planetary Society, the spacecraft is fueled by photons of sunlight, which bounce off enormous solar panels. Once the ship reaches Earth orbit, its "sails" will unfurl and, if all goes as planned, the spaceship will slowly accelerate. Project director Lou Friedman calculates that solar-sail-equipped ships can accelerate from 100 mph on day one to 10,000 mph after 100 days under sail. And with the constant accelerative force of the sun's photons, a solar sail could reach a speed of 100,000 mph in three years, making it a plausible way to explore deep space.